This stops microwaving after about nine seconds and resets itself, it is cooking for this time as a cup of water heats up after a few tries. If you unplug the supply to the inverter it cuts out after 3 seconds as they normally do. Be grateful for any ideas.
Siemens 84E562GB microwave.
Thanks
Check for arcing in the cabinet. Remove glass base and check around all seams. Not always easy to spot. Found this is more likely to occur when only a small load in the oven, ie testing with a small cup of water rather than a big jug